I have had a VS 57 head unit since 1981 which I was planning for a SBC. However that project became a big-block (capable of more volume than this blower can provide) and thus the supercharger has been sitting 30 years! I am planning to install this blower on an 06 Chevy Colorado I 4. After reading your comments, it appears I should not only have you rebuild my unit (inter-granular corrosion) but also convert to fixed pulley design. Is this a recommended option for my Colorado. The variable pulley with increased boost initially should really wake up this motor. My stock I 4 has 10:1 compression - however with computer controls, I can expect the spark retard to control the pre-ignition during the lower rpms. However, converting to a fixed serpentine pulley with the factory idler pulley would certainly be easier to engineer!

If I stay with the VS design, what is the amount (pounds)of idler pulley pressure needed to overcome the head unit's spring and vacuum piston pressure. I will most likely need to use a shorter lever arm and therefore a stronger spring rate in this custom application.

In many of your posts, you suggest a phone call to discuss particulars of specific applications. What is the best time of day and day of the week to contact you?

Thank you in advance for you response and once again for your willingness to share your considerable knowledge with the rest of us!

David, I have installed modified VS units on big block engines, Cam change is very beneficial, Your engine with ten to one compression is much better suited for use with a fixed pulley because an on... more

John, Thank you for your quick response and sharing your thoughts! Wow, 14 PSI on your Toyota is huge! I never thought this blower could push that much volume. I agree with you that with 10:1 I will... more

David, I have some serpentine pulleys but have found that Studebaker pulleys work well on S/C and AC pulleys can often be used for the crank drive all with easy to find V belt length belts. The old... more